1. Field of the Invention
The present invention relates to data networking. In particular, the present invention relates to a method and apparatus for a network probe to synchronize enhanced modes of operation between two nodes connected via a point-to-point link, into which link the network probe is inserted.
2. Description of the Related Art
With reference to FIG. 1, prior art data networks generally utilized one or more shared media hubs, e.g., hub 10. Multiple nodes, or end user workstations, e.g., workstations 1, 2 and 3, were coupled to a shared communications that was, in turn, coupled to a port on the shared media hub. The hub 10 had multiple ports (e.g., ports 11, 21, 31), each coupled to a different shared communications medium. High end workstations, or servers, such as file servers or print servers, were also coupled via a dedicated or shared communications medium to a port on the shared media hub.
As the applications running on these data networks became more mission critical, and bandwidth utilization of the shared communications media increased, it became advantageous to monitor, for example, the performance and the error rates of data traffic on the shared communications media to facilitate proper operation of the data network. To accomplish this monitoring, network monitoring devices were configured into shared media hubs, or coupled to the port (41) of a shared media hub via a communications medium (40) as stand-alone devices (e.g., probe 4). In either configuration, the monitoring devices were typically referred to as probes. The probes would promiscuously monitor the data traffic on all shared communications media in the network and look at, for example, performance and error statistics, data traffic patterns and typical data flows across the shared communications media.
As shown in FIG. 2, as performance requirements of prior art data networks continued to increase, and additional performance intensive applications were employed, the shared communications media coupled to the shared media hubs were typically divided into multiple network segments (e.g., network segments 201, 202 and 203) to reduce data traffic on each segment, although all network segments were still in the same collision domain, i.e., the network segments were not electrically isolated. Data communication between these segments generally utilized well known backbone, rather than switching, technology.
As performance requirements continued to increase to meet traffic demands, switches such as switch 220 illustrated in FIG. 2 were used to segment the network into multiple collision domains. Segmenting the network into multiple collision domains prevented a data packet from one segment (e.g., segment 201) traversing the network to another segment (e.g., segment 202) unless the data packet was destined to a particular device on the other segment. Such a determination was based, for example, on a destination address specified in the data packet.
The problem, however, in monitoring network performance in such an environment utilizing probes was that a single probe was required for each segment in order to promiscuously monitor the data traffic on that segment. With reference to FIG. 3, as the data networks became highly segmented, it became evident that it was impractical to attach a probe to each segment in the network to promiscuously monitor all traffic. Rather, network administrators tended to concentrate probing activities to highly concentrated server farms or segments in the network where the traffic was the busiest, for example, a segment from a switch to a file server. These file servers were typically coupled via a dedicated point to point communications medium to a port on a switch to provide, for example, a data communications rate of 10 megabits per second, 100 megabits per second, or even 1000 megabits per second, to the file server. Connecting the file server using a dedicated point to point communications medium to the switch 220 formed a single station network segment. In a single station network segment, it was impossible to attach a probe to that segment to promiscuously monitor network traffic because only a single port was necessarily available for coupling the segment to the switch. To overcome this limitation, a multiport repeater was inserted between the switch and the file server, e.g., repeater 233 between workstation 3 and switch 220 in FIG. 3, thereby providing additional ports (on the inserted multiport repeater) to facilitate connection of a probe (e.g., probe 235) into the segment.
Although switch 220 in FIG. 3 shows only six ports for purposes of illustration, it is understood that a switch may have sufficient ports to support, for example, ten, twenty, or more servers. In such a situation, it becomes impractical to attach a repeater between every server and switch port to promiscuously monitor data traffic, due to the increased cost, space, and asset management responsibilities encountered as a result of the additional equipment. In addition, for each communications medium that was to be monitored, that network segment would have to be taken down, the server disconnected from the switch, the repeater inserted into the communications medium, and the server communication reestablished. This process would be highly disrupting to data communications in the network. Moreover, in attempting to diagnose a performance problem, one would be required to shut down the network segment, insert a repeater, and couple a probe to the repeater in order to collect monitoring data. By the time the probe was operable, the performance problem may well have disappeared.
With reference to FIG. 4, a prior art probe as may be utilized in a typical switched data networking environment is illustrated. Multiple network segments 201, 202 and 203 are coupled to a shared media hub 200. Each segment is connected to separate modules 204, 205 and 206, respectively, within the hub. Each of the hub modules are coupled via a dedicated communications medium 401, 402 and 403 to an individual port 404, 405 and 406 on a switch 220. (Alternatively, segments 201, 202 and 203 may each be a dedicated communications medium, in which case, the segments would be directly coupled to respective ports 404, 405 and 406 on switch 220.) Ports on the switch are additionally shown connected either to a dedicated network device, e.g., device 2 (perhaps an end user workstation or a server), or connected to prior art probe 400. More specifically, a port (e.g., port 407) on the switch may be connected to a port (e.g., port 408) on the probe. Another port (409) on probe 400, in turn, is coupled to a network device such as workstation 1. While the network device illustrated is a workstation, it is appreciated that the network device may be another switch, a server, or other network device. Probe 400 includes circuitry for repeating data packets between the switch and the network devices coupled to the probe.
The probe 400 utilizes internal bypass circuitry in promiscuously monitoring the communications medium coupling network devices 1 and 3 to the probe. The probe promiscuously monitors all traffic between the hub 200 and switch 220 destined for or received from either network device 1 or network device 3. All data traffic is captured, and potentially saved, e.g., for some form of analysis or statistical compilation. The probe analyzes those packets according to, for example, the remote monitoring standards RMON I or II. These standards promulgate, for example, specific statistical characteristics, such as user history, performance and error rates and traffic patterns between different workstations on the network across all layers of the International Standards Organization (ISO) Open Systems Interconnection (OSI) seven layer networking model.
Today, network devices, or nodes, are capable of operating in any one of a number of modes, defined in terms of the media type(s) over which the nodes transmit and receive data, the speed of the data transmission, full or half duplex communication of the data, etc. Thus, IEEE Standard 802.3u, clause 28, provides for Auto-Negotiation. Auto-Negotiation allows a device connected at one end of a point to point communications medium to advertise modes of operation of which it is capable to a device at the opposite end of a point to point link, and to detect corresponding information that the other device may be advertising. However, when a prior art probe is inserted between such nodes in a point to point link, the nodes are no longer able to directly negotiate the highest common mode of operation between them by means of the Auto-Negotiation function. What is needed is an improved network probe that negotiates and synchronizes enhanced modes of operation between two nodes connected via a point-to-point link, into which link the network probe is inserted.